Malicious PDF — malware analysis report

Static analysis result for SHA-256 87a797d9ed87c786…

MALICIOUS

PDF

15.7 KB
MD5: a5c4636bf77c13146bd474a5a89f8b02 SHA-1: 8a02128fc4a6cae3f4488a08b7d513e4a2e5fb1a SHA-256: 87a797d9ed87c786ebd9496b5d06eb34ea1b161be49d560a151d62107b733a4a
166 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1204.002 Malicious File T1566.001 Spearphishing Attachment

The PDF file contains embedded JavaScript, indicated by multiple heuristic firings including 'PDF_JAVASCRIPT', 'PDF_JS', and 'PDF_EVAL'. The 'PDF_JS_LARGE_COMMENT_PADDED_EVAL' heuristic suggests a stager designed to obfuscate its malicious intent. The embedded JavaScript streams, named 'javascript_obj0006_000.js' and 'legacy_pdfkit_stage_000.js', are likely responsible for downloading and executing a secondary payload. The ClamAV detection 'Pdf.Exploit.Agent-36086' further confirms the malicious nature of the file.

Heuristics 7

  • ClamAV: Pdf.Exploit.Agent-36086 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Exploit.Agent-36086
  • eval() call high PDF_EVAL
    eval() found — commonly used for obfuscated exploit execution (matched inside decoded stream)
  • Large comment-padded JavaScript eval stager high PDF_JS_LARGE_COMMENT_PADDED_EVAL
    PDF JavaScript contains a very large stream padded with long random-looking block comments around String.fromCharCode and eval. This is an exploit-kit obfuscation shape used to bury a decoder and recovered stage inside noise, not normal PDF form automation.
  • JavaScript action low PDF_JAVASCRIPT
    PDF contains a /JavaScript action. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
  • Embedded JS stream low PDF_JS
    PDF references a /JS stream. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
  • String.fromCharCode low PDF_FROMCHARCODE
    String.fromCharCode found — used to construct payload strings dynamically. Common in benign JavaScript libraries for codepoint manipulation, so this alone is informational; weaponised use is also caught by the dedicated fromCharCode-stage and exploit-shape rules. (matched inside decoded stream)
  • Suspicious extracted artifact info EXTRACTED_FILE_STATIC_TRIAGE
    One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0006_000.js
49dd13286f8d157c7bc811d531e1432f4872e7202491dfb543e05353304228ef
pdf-javascript-stream PDF /JS object 6 at offset 0x143 424418 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 2 eval/decoder/string-building token(s). Carved artifact contains 42 long base64-like blob(s).
legacy_pdfkit_stage_000.js
78338bd30f2ecf48f6fa40625277e782e8048d2cec89c1b0e567e54b704c5481
deobfuscated-js double percent-decoded annotation JavaScript at offset 0x143 262144 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 640 long base64-like blob(s).